My BF feels my pussy way tighter after cuckolding him than years ago [Cuckold]

Hello guys! I was talking about sex with my BF a few days ago while cuddling because for some reason I was feeling lately like his dick was growing a bit in thickness, I know it sounds kinda weird, but it was like his dick was hurting my pussywalls more than usual and even when the sensation was becoming more pleasureable and painful at the same time (which I really enjoy)… I couldnt understand why it was happening at all. I even thought that maybe he was just taking hormones or something like that? He laughed real bad at me when I mentioned this to him and just said that he felt that my pussy walls were becoming tighter than usual and that he could feel a lot more tension, like he could feel the presure when I make them tight at will when I was getting aroused… it made a lot of sense to me right after.